By use of phosphorescence spectroscopy and chemical modifications, a clinically acceptable method of determining porphyrin concentrations in blood, urine, and other materials can be developed. Our aims are: 1. To increase sensitivity and selectivity of porphyrin and metalloporphyrin analysis over present methods. 2. To determine the usefulness of metal probes in biological systems. 3. To develop a method with minimum interference from other materials commonly found in biological samples, and thus eliminating need for rigorous separation procedures. 4. To investigate the potential usefulness of a combination of simple separation procedures with luminescence measurements of porphyrins.